The invention relates to a method for acquiring a traffic state of vehicles and to an apparatus for acquiring such a traffic state.
For the goal-oriented use of traffic guidance systems, a reasonable adjustment of the switching phases of light signal apparatuses, and for a determination of roadway construction measures that is in accordance with traffic conditions, a computer-supported simulation and forecasting of traffic flow that is as comprehensive as possible is necessary. In order to match the programs used for this purpose with actual conditions, comprehensive information about the actual state of traffic in the areas under consideration must however be present. In densely populated areas in particular, it is hereby not sufficient to acquire only individual roadways with regard to traffic flows; rather, an image of the traffic situation that is as complete as possible, including possible alternative routes, detours, etc., is required.
The acquisition of the actual traffic state that is important for the optimization of the traffic flow has up to now been carried out via measurement installations at the infrastructure, for example in street traffic via measurement loops in the roadway or by means of traffic counts that are highly personnel-intensive. However, these techniques are very strongly locally limited, and do not allow an overall view. In addition, their diagnostic effectiveness may be low, according to whether the measurement location has been chosen correctly or incorrectly. In addition, measurement apparatuses at the infrastructure are stationary and are connected with significant costs both for installation and for maintenance. For these reasons, as a rule these measurement methods are limited to few locations.
It is an object of the invention to provide a method for acquisition of a traffic state of vehicles over a large area.
According to the method of the present invention for acquiring a traffic state of vehicles, from a body located at a distance above a surface of the earth, recording an image of the region located underneath the body at or above the surface of the earth and that has a lateral diameter of at least one kilometer. The image is recorded with a grid dimension that is small enough that densities of at least one particular type of vehicle located in the region can be recognized up to a predetermined maximum density. The recorded image is evaluated with regard to at least one density for at least one type of vehicle.
According to this solution, from a body located at a distance above the surface of the earth an image is recorded of a region that is located underneath the body on and/or above the surface of the earth and that has a lateral diameter of at least one kilometer, said image being recorded with a grid dimension that is small enough so that densities of at least one of a particular type of vehicle located in the region can be recognized, up to a predetermined maximum density, and the recorded image is evaluated with regard to at least one density at least of the one type of vehicle.
As a body, a geosatellite orbiting the earth is preferably used. Due to its great distance from the surface of the earthxe2x80x94on the order of 100 kilometersxe2x80x94such a satellite has the advantage that particularly large regions, of for example 50xc3x97100 kilometers surface area, and in any case a region having a diameter on the order of magnitude of 10 kilometers, can be monitored.
In this way, traffic of every type and/or type of vehicle, including land vehicles not bound by rail, for example all types of passenger vehicle and/or truck, rail-bound vehicles, for example all types of railway trains for passenger or freight traffic, water vehicles, for example all types of passenger and freight ships, both at sea and on inland waterways, as well as aircraft, for example all types of passenger and freight airplane, can advantageously be monitored rapidly and reliably over a larger area than was previously known or possible. In particular, vehicles can advantageously be monitored, in particular simultaneously, both in a manner separated according to the species and/or type of vehicle and also in a manner disregarding the species and/or type of vehicle.
With a single satellite orbiting the earth, every 2 to 4 days individual images and chronological sequences of images of the same region can be produced.
As a body, a geostationary geosatellite can also be used, which advantageously enables a constant monitoring of traffic in a region of almost the size of an entire hemisphere, for example the ship traffic in the Atlantic or Pacific.
From a geosatellite, images of the large regions can be produced optically with sufficiently high resolution, but this type of recording depends on the time of day and on the weather. If in contrast radar radiation is used for recording the images, the images can advantageously be recorded at all times of day and in all types of weather. However, a radar radiation and a radar system must be used that enable images having a sufficiently small grid dimension, corresponding to a sufficiently high resolution. A dimension of two meters is regarded as the lower limit of the grid dimension, at least in relation to street traffic, in order to enable differentiation of lane positions. Densities of street vehicles can thereby be unambiguously recognized and allocated, because the vehicles have different degrees of reflection than do the roadways, and corresponding differences of brightness therefore exist in the recorded images.
Instead of a body in the form of a satellite, a body in the form of an aircraft can also be used in the inventive method, whereby as an aircraft an airplane can primarily be used, but for example a balloon or the like is also possible. From the airplane, images of regions of a width of five to seven kilometers can for example be realized, and in any case regions comprising a diameter of the order of magnitude of 1 kilometer.
In order to remain independent of the time of day and the weather conditions in this case as well, it is again recommended that the images be recorded not optically but rather using radar, advantageously SAR. Here as well, in relation to street traffic two meters is regarded as the lower limit of the grid dimension.
In any case, it is thus advantageous to record an image by means of a radiation of radar.
If the images are recorded with the aid of interferometry and/or the Doppler effect, it is advantageously possible to acquire velocities of the vehicles in addition to vehicle densities.
The inventive method is particularly advantageous for the acquisition over a large area of a state of street traffic and for monitoring and guiding the street traffic in large cities, but is also suitable for use in smaller cities and/or rural areas, but is not limited to this, but rather can, as already mentioned, in principle also be used for monitoring the movement of railway trains, ships and/or aircraft, particularly in harbor areas and airport areas.
An advantage of the inventive method can be seen in its suitability for the use of georeferencing, which enables a rapid and precise allocation between a point in the region and the corresponding point on the recorded image of this region. In an advantageous realization of the inventive method, a spatial allocation is created between a vehicle density recognized in an image of the region and a roadway of the region, using georeferencing, which, in particular given images recorded from artificial geosatellites, enables a spatial allocation of vehicle densities to the respective roadways.
A monitoring of modifications of the traffic conditions can advantageously be achieved if after recording an image of the region at least one additional image of the same region is recorded and is likewise evaluated with regard to vehicle densities found in the region, and if at least two recorded images are compared with one another. In this way, a direct optimization, for example in relation to street traffic, of the control algorithms of traffic guidance systems and traffic light phases can advantageously be realized by means of a comparison before and after the optimization technique. In addition, intended modifications by means of street construction techniques can advantageously be monitored, and existing simulation programs can be precisely matched.
In this case, it is particularly advantageous if at least a sequence of two images of the region is produced by individual momentary exposures that succeed one another chronologically within one hour. Such a sequence of images can advantageously be used for the acquisition of the traffic state and the chronological modification thereof in real time, or can also be used at a later time, for example in reference to the street traffic for the production of current traffic conditions for traffic information, the direct controlling of traffic guidance systems, and for the adjustment of traffic flow simulations, whereby in addition a direct optimization of the control algorithms of traffic guidance systems and traffic light phases can be realized by a before/after comparison. The evaluation of the exposures can take place manually, or else, in a shorter time and with a lower personnel expense, by machine, if a system is available for the recognition of vehicle density in the images and for the spatial allocation of the vehicle densities to the respective roadways.
The actual evaluation of the exposures can take place already in the body, for example on board the satellite or aircraft. An advantageous arrangement, suitable for this purpose, for acquiring a traffic state is when the body, located at a distance above the surface of the earth, in particular a geosatellite orbiting the earth, is a geostationary geosatellite or is an aircraft.
According to an advantageous construction of the inventive arrangement, the evaluation unit converts a particular information content of a recorded image into coded data signals.
The evaluation unit advantageously produces georeferenced coded data signals, with the aid of which a reference to land maps for roadways to be examined, and thereby a spatial allocation of vehicle densities to respective roadways, is produced.
From the coded data signals, an item of information concerning a traffic state in the relevant region is obtained, preferably using a processing unit for a processing of the data signals in order to obtain an item of information concerning a traffic state in the region. The processing unit is preferably located on the surface of the earth, in particular in stationary fashion.
An item of information concerning a traffic state in the region is supplied for a further use, preferably in the form of data that are relevant only for this use, and preferably in a use unit provided for this use. For various uses concerning a traffic state, different use units can be used, which are preferably located on the surface of the earth, in particular in stationary fashion.
In the following specification, the invention is explained in more detail in exemplary fashion on the basis of the figures.